Hi, On Wed, 06 May 2009 15:28:59 +0900 (JST), Ryusuke Konishi wrote: > If we treat read-only mount as the latest snapshot at the time (though > we didn't take this interpretation), the transitions can be reduced > to: > > * r/w -> r/w. Allowed. > * r/w -> snapshot. Allowed if no checkpoint number was given (or the > latest checkpoint was specified) > * snapshot -> r/w. Allowed if it's the latest one and no r/w is there. > * snapshot -> snapshot. Only if it's the same. > > Right? Ah, I had forgotten garbage collection (GC). GC can break checkpoints which are not marked as snapshot. ro-mount cannot coexist with rw-mount because GC works while an rw-mount is there. Sorry, the above interpretation was not easily realized. > But it still needs test_exclusive_mount(). > > The test_exclusive_mount() may be eliminable by adding rw-mount-exists > flag on the_nilfs struct. I'll take some thinking. The elimination of test_exclusive_mount() was possible by this method if we can treat ro-mount as the latest checkpoint at the time. I'd like to consider if a similiar elimination is possible in case that ro-mount and rw-mount cannot coexist. Regards, Ryusuke Konishi -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
